马尾松芽苗移栽根菌根化育苗试验

在非松林砍伐迹地上或贫瘠的地区应用芽苗移栽截根接种Pt菌剂能有效促进苗木的生长，苗高提高了6．25％－21．2％，地径提高了6．67％－20％、侧根总数提高了100％－110％、菌根感染率提高了18．8％－110％。在松林砍伐迹地上进行的试验结果表明，Pt菌剂与乡土菌根菌对Pt菌有一定的换制作用，接种苗木的菌根感染率有所下降，对苗木的生长作用不明显。截根接种Pt菌剂及截根未接种的苗木冬季的苗高生长情况可以看出，该技术能有效促进苗木的木质化。     

稳态营养对湿地松容器苗Pt外生菌根形成及生长效应研究

在非控制条件下，按稳态矿质营养理论与技术，对接种与不接种Ｐｔ外生菌根菌剂的湿地松芽苗，分别以０％、５．３％、６．４％、７．５％营养物相对添加速率进行施肥处理。通过观测苗木生长，根系和菌根发育，生物量积累，以及叶片营养元素和叶绿素含量，研究湿地松芽苗Ｐｔ外生菌根形成的外界营养水平及生长效应。结果表明，Ｐｔ接种苗平均株同、地径、株干重基本上随营养物添加速率提高而提高，其中７．５处理比０处理分别提高２６     

Pt菌剂对高阿丁枫苗木生长的影响

进行高阿丁枫接种Pt菌剂的育苗效果试验。结果表明:Pt菌剂对高阿丁枫苗木的生长有明显的促进作用。经Pt菌剂处理后高阿丁枫苗木的苗高、地径、侧根数、主根长、地上部分鲜重、地下部分鲜重、全重及一级侧根长分别较不经Pt菌剂处理的对照提高了23.1%、8.7%、23.1%、21.0%、25%、33.3%、26.7%、49.2%。且苗木的径高比不失衡。     

湿地松幼苗矿质营养与天然外生菌根及其效用研究

湿地松幼苗盆栽土混入松林土感染天然外生菌根，设Ｎ、Ｐ、ｋ、ＮＰ、ＮＫ、ＰＬ、ＮＰＫ、全肥处理及对照，观测幼苗生长和外生菌根感染率。结果显示，全肥、ＮＰＫ、ＮＰ、Ｐ处理效果较好。全肥和ＮＰＫ处理地径比ＣＫ均提高４６．２％，ＮＰ株高比ＣＫ提高２４．４％，Ｐ、ＮＰ、全肥生物量分别比ＣＫ提高１２．７％、１０．６％、６．０％；天然菌根感染率与施Ｎ呈负相关，与幼苗生长关系不密切。指出了根据营养需要进行配方施肥及筛选优良菌种、进行人工接种对培育壮苗的重要性     

接种彩色豆马勃菌株对松树苗生长的影响

马尾松(Pinus massoniana)和湿地松(Pinus elliottii)苗根系感染彩色豆马勃(Pisolithus tinctorius)菌株形成菌根后,对苗木的高、地径和侧根生长均存在显著的促进作用。但不同的接种方法,存在一定的差异,其中A处理(点穴式接种)的感染率最高,马尾松苗69.4%,湿地松苗61.7%;D处理(拌土接种式)的最低,分别是27.2%和43.1%。与对照相比,A处理马尾松和湿地松苗高分别增加20.1%和32.0%;地径分别大24.0%和29.0%;侧根数量分别多79.6%和55.8%;而D处理苗高分别增加8.0%和3.8%,地径分别大4.0%和16.1%,侧根数量分别多12.3%和29.3%。     

四川松树截根菌根化育苗造林效应

使用优良Pt固体菌剂，对湿地松、火炬松与马尾松进行了截根菌根化接种育苗造林。结果表明，截根菌根化接种方法，使供试松苗形成了大量菌根，Pt菌根指数大于60，苗木质量明显改善，用菌根化苗木造林，幼林成活率与生长量都明显提高。菌根化幼林还具有一定抗旱性和抗污染能力。     

湿地松幼苗矿质营养与天然外生菌根及其效用研究

湿地松幼苗盆栽土混入松林土感染天然外生菌根，设Ｎ、Ｐ、Ｋ、ＮＰ、ＮＫ、ＰＫ、ＮＰＫ、全肥处理及对照，观测幼苗生长和外生菌根感染率。结果显示，全肥、ＮＰＫ、ＮＰ、Ｐ处理效果较好。全肥和ＮＰＫ处理地径比ＣＫ均提高４６．２％，ＮＰ株高比ＣＫ提高２４．４％，Ｐ、ＮＰ、全肥生物量分别比ＣＫ提高１２．７％、１０．６％、６．０％；天然菌根感染率与施Ｎ呈负相关，与幼苗生长关系不密切。指出了根据营养需要进行配方施肥     

湿地松苗木菌根化及其稳态营养的研究

利用菌根化及其稳态营养对湿地松容器育苗的试验进行分析，结果表明：Ｐｔ菌接种的上水平营养处理所形成的外生攻根感染率分别高于中、下、ｃｋ处理的１０８％、１０９％、１３０％；Ｐｔ菌接种与自然感染的苗木高、径生长只有在上水平营养自理中差异显著，而中、下、ｃｋ等处理差异不显著；在Ｐｔ菌接上，水水平营养与相庆的ｃｋ的苗木高、径生长差异极显著，中水平营养与相应的ｃｋ的苗高生长差异显著、径生长差异不显著；在自然因     

3种菌根菌对栓皮栎接种的效应

菌根技术对于优质苗木的培养具有重要的意义.应用3种不同的外生菌根菌剂对栓皮栎幼苗进行土壤根际处理,并对其幼苗菌根菌的感染能力以及促进生长效果进行了分析研究,获得以下结果:菌剂处理对栓皮栎苗高、地径、干质量、侧根等方面有显著的促生作用;菌剂处理提高了苗木净光合速率及叶绿素的含量;筛选出了北京地区促进栓皮栎幼苗生长的优良菌种绵毛丝膜菌.     

火炬松容器苗侧根的生长与彩色豆马勃外生菌根的关系

<正> 用接种彩色豆马勃菌 (Pisolithus tincto-rius,以下简称Pt)的火炬松(Pinus taeda L.)容器苗,在较差的立地条件上造林,可以提高苗木的生长量和保存率;但在一般立地条件上,这种容器苗并不比具有天然外生菌根的苗木好,也不比接种Pt的裸根苗好。由于容器的局限性,减少了松苗的根量,致使幼小的苗木根系盘旋生长,与营养土一起     

Browsing Damage on Pine (Pinus sylvestris and P. contorta) by a migrating moose (Alces alces) Population in Winter: Relation to Habitat Composition and Road Barriers

In Scandinavia, moose (Alces alces L.) sometimes cause severe browsing damage to economically-important pine. Moose-vehicle accidents have spurred construction of fences along roads, and these may interfere with moose migration between summer and winter ranges, or the road alone may be a barrier. If this happens and moose build up along roads, landowners may suffer economically. Therefore, this study investigated whether roads, fences or other factors influence the use of young pine stands by moose. Eighty stands along roads in northern Sweden were evaluated in which individually-browsed branches were counted on 9972 pines. Moose browsing was not significantly related to birch (Betula pendula Roth, B. pubescens Ehrh.) density, nor did it differ between pines (Pinus contorta Douglas or P. sylvestris L.). However, increased pine density, site productivity and proximity to a highway were associated with increased browsing. Further large-scale studies are needed to understand moose habitat selection and the effects of roads.     

Effects of Root Freezing on the Physiology and Growth of Picea glauca,Picea mariana and Pinus banksiana Seedlings Under Different Soil Moisture Regimes

The root systems of 2-yr-old Picea glauca, Picea mariana and Pinus banksiana seedlings were submitted to various frost temperatures during an artificial frost to induce different levels of root damage. Frost-damaged and control seedlings were placed in a greenhouse under high and low soil moisture regimes. Seedling growth and physiology were evaluated periodically. Seedling survival was reduced when root damage reached levels of 60-80%. Root systems of all three species showed partial to total recovery by the end of the experiment. In general, root freezing damage caused reductions in seedling growth, with these reductions becoming less significant over time. Root damage had little to no effect on black spruce and jack pine seedling physiology, while white spruce CO 2 uptake decreased with increasing root damage. Shoot nitrogen content of all three species decreased slightly with increasing root damage.     

Stand Structure in Pine,Spruce and Deciduous Forests: A Comparison Between Finnish and Russian Karelia

This study investigated the stand structure in pine, spruce and deciduous forests in the border district of Finland and Russia. A total of 46 mature forest stands was selected as pairs, the members of each pair being as similar as possible with respect to their forest site type, age, moisture and topography. The stands were then compared between the two countries by means of basal areas and number of stems. The proportions of dominating tree species were 2-12% lower, and correspondingly the proportions of secondary tree species higher, in Russian forests. The density of the forest stock was also higher in each forest type in Russia. The forests in the two countries differed most radically in terms of the abundance of dead trees. The amount was two to four times higher in Russian deciduous and spruce forests, and in pine forests the difference was 10-fold. The stand structures indicated that Russian coniferous stands, in particular, were more heterogeneous than intensively managed pine and spruce stands in Finland.     

Growth and Terminal Bud Formation in Picea abies Seedlings Grown with Alternating Diurnal Temperature and Different Light Qualities

The root collar diameter and the height:diameter ratio are of particular importance in container-grown seedlings where a high density in the containers may produce spindly seedlings. Temperature regimes and light quality are known to affect plant growth. The aim of this study was to identify responses in Picea abies (L.) Karst. seedlings grown with light providing different red:far-red ratios and under temperature regimes with alternating day (DT) and night temperature (NT) from negative (DT < NT) to positive (DT > NT) difference (DIF) between DT and NT. Experiments were conducted in controlled environment chambers and in a daylight phytotron. Only limited thermoperiodic responses appeared in P . abies seedlings with respect to seedling height and dry weight accumulation. The formation of terminal buds, however, was clearly delayed in seedlings grown at negative DIF. The results indicate a requirement for day extension light that is high in far-red, to prevent terminal bud formation under natural short-day conditions. An extended study should be conducted to clarify the minimum level of light intensity and the optimal light quality needed to prevent terminal bud formation under natural short-day conditions.     

Decomposition and nutrient loss from prunings of different contour hedgerow species in tea plantations in the sloping highlands of Sri Lanka

Contour hedgerows of multipurpose tree species in the sloping tea lands of Sri Lanka are expected to reduce soil erosion and also add significant amounts of plant nutrients to the soil via periodic prunings. The objective of this experiment was to characterize the biomass decomposition pattern and quantify the amount of nutrients added through prunings of six tree species (Calliandra calothyrsus, Senna spectabilis, Euphatorium innulifolium, Flemingia congesta, Gliricidia sepium and Tithonia diversifolia) currently being used in hedgerows associated with tea. Withered leaf and stem prunings (50 g) were enclosed in 2-mm litter bags, placed at 5-cm depth and retrieved after one, three, six, nine and 12 weeks. Loss of initial dry weight, N, P and K was measured. Single exponential decay function adequately described both dry weight and nutrient loss. Tree species differed significantly in their rate of breakdown with decomposition constants (k) varying from 0.0299 to 0.2006 week⁻¹ for leaves and from 0.0225 to 0.0633 week⁻¹ for stems. Gliricidia showed the highest k for leaves with the rest in the following descending order: Senna > Tithonia ≥ Euphatorium > Calliandra > Flemingia. A similar pattern was observed for loss of all nutrients with Calliandra and Flemingia always having lower k values than the rest. Although N immobilization was not observed, immobilization of P and K was observed during the first week of incubation in some species, particularly in stem prunings. Annual biomass of prunings differed significantly between tree species in the following descending order: Calliandra > Senna > Flemingia > Tithonia > Gliricidia > Euphatorium. Calliandra added the greatest amount of nutrients annually to the soil with Euphatorium adding the least. Calliandra prunings provided the annual total K requirement and 49% of the N requirement of mature tea. However, none of the species provided more than 5% of the P requirement. It is concluded that among the tree species tested, Calliandra and Flemingia are the most suitable for contour hedgerows in tea plantations of this agroclimatic region because of their higher soil nutrient enrichment capacity and slower decomposition rates which would minimize leaching losses. This revised version was published online in June 2006 with corrections to the Cover Date.     

CAD与建筑设计的关系

本文分析了CAD在设计中引起的正面和负面影响,并进行了系统的阐述,从而使设计者在应用中能够保持客观的态度。     

Growth of Phlebiopsis gigantea in wood of seven conifer species

Heterobasidion parviporum and Heterobasidion annosum are widely distributed root‐rot fungi that infect conifers throughout Europe. Infection of conifer stumps by spores of these pathogens can be controlled by treating fresh stumps with a competing non‐pathogenic fungus, Phlebiopsis gigantea. In this study, growth of three Latvian strains of P. gigantea and the biological control agent ‘Rotstop’ strain was evaluated in stem pieces of Norway spruce, Scots pine, lodgepole pine, Douglas‐fir, Weymouth pine, Siberian larch and Sitka spruce. The growth rates of one H. parviporum and one H. annosum isolate were also measured in the same stem pieces. The growth rate of P. gigantea varied greatly in wood of different conifer species. It was higher in the three pine species, lower in Norway spruce and lowest in Sitka spruce and Siberian larch, and in Douglas‐fir, this fungus did not grow. The largest area of wood occupied by P. gigantea was in lodgepole pine. Growth of Latvian isolates of P. gigantea in the wood of Pinus and Picea species was comparable to that of the Rotstop isolate. Consequently, stump treatment with local P. gigantea isolates should be recommended. However, our results suggest that Douglas‐fir stump treatment against Heterobasidion by P. gigantea may be ineffective and other stump treatment methods should be considered.     

Effects of Seed Weight and Seed Type on Early Seedling Growth of Pinus sylvestris under Harsh and Optimal Conditions

The effects of seed weight and seed type on seedling growth of Pinus sylvestris (L.) were studied by seeding individually weighed orchard and stand seed in different mixtures under harsh (direct seeding in field) and optimal (seeding in nursery) conditions. In the nursery experiment an increase in the seed weight from 3 to 7 mg increased the seedling height by 10-27% and total weight by 27-113%, and decreased the height/diameter ratio by 5-6% after 2 yrs. With elimination of seed weight effects, orchard seedlings were 2% taller than stand seedlings in year 2. Without elimination of seed weight effects, orchard seedlings were 7-13% taller. In the field experiment an increase in the seed weight from 3 to 7 mg increased seedling height by 18-65%, stem volume by 81-274% and the number of top-buds by 23-34% in year 5. After elimination of seed weight effects, orchard seedlings were 7-13% taller than stand seedlings and without elimination of seed weight effects 20-21% taller after 5 yrs. Even after elimination of both seed weight and genetic effects orchard seedlings were 3-9% larger than stand seedlings in the field experiment. In conclusion, the influence of seed weight and seed type on growth traits and slenderness is highly significant and the influence seems to be greater in harsh conditions.     

Potential to harness superior nutritional qualities of exotic baobabs if local adaptation can be conferred through grafting

Baobab leaves form an important part of the local diet in Sahel countries and elsewhere in Africa. Existing leaf nutritional data and agroforestry performance information are based solely on Adansonia digitata L., the baobab of continental Africa. The introduction potential of Adansonia species from the center of diversity in Madagascar and from Australia remains untapped. To assess this potential, the mineral contents and B₁ and B₂ vitamin levels of dried baobab leaves were determined for five-year old trees of A. digitata, A. gibbosa (A. Cunn.) Guymer ex D. Baum, A. rubrostipa Jum. & H. Perrier (syn. A. fony Baill.), A. perrieri Capuron and A. za Baill. grown in an introduction trial in Mali. Nutritional data were evaluated against survival and vigor to identify promising germplasm. Leaf vitamin and crude protein contents were highest in the Madagascar species, especially A. rubrostipa (B₁ 88 mg 100 g⁻¹, B₂ 187 mg 100 g⁻¹, protein 20.7% dry weight). However, the local species far outperformed the introductions in survival, tree height, basal diameter and resistance to termites. We suggest grafting as a way of harnessing the vigor of well-adapted local baobab varieties to the superior nutritional profiles of A. rubrostipa and others. Cross-species grafting tests in Adansonia were successful, thus creating new agroforestry possibilities with different scion/rootstock combinations.     

Modelling of adequate pretwist for obtaining straight timber

Abstract

Wood in general and wooden studs in particular are often distorted owing to uneven shrinkage during the drying process in the sawmill. Twist is often the most detrimental of all types of distortion, and it is caused by spiral grain in combination with variations in moisture content. For sawmills, the objective is to produce dried, straight boards, and one method of dealing with boards with excessive spiral grain is to sort them out and then dry them in a pretwisted position to obtain straight boards after drying. A model using the finite element (FE) method for the simulation of drying twist distortions was first calibrated against laboratory experiments in which boards were dried with and without restraints and pretwists. After the calibration, the FE results were compared with industrial test results for boards that were dried without restraints or with restraints with zero pretwist, i.e. straight restraints. The FE model used an elastic–ideally plastic material model to obtain permanent deformations. The calibration was to set the yield stresses so that there was a good match between FE results and results from the laboratory experiments. The comparison between the industrial test results and the FE results showed that the FE model is capable of realistic simulations of drying boards with and without restraints and presumably also pretwists.